Similar with first season reward for Keystone Master, second one - Soultwisted Deathwalker, but more brighter howling vortex of tormented souls. You have to attain a Mythic+ Rating of at least 2000 during Shadowlands Season Two, instead of completing all Shadowlands dungeons at level 15+. Since the new system is quite flexible, you can type them in different ways:
Complete every level 15 dungeon on both Tyrannical and Fortified weeks.
Complete dungeons of different levels on different weeks, for example, level 16 with one modifier and level 14 with another, or one level 16 dungeon and another level 14
Complete each level 24 dungeon and any one week.
All these thing required a lot of time and dexterity, so we can help you with this :) You can buy Soultwisted Deathwalker for EU or US Region with ReinwinBoost team!